@tig said:

Also remember that there is an absolute 'smallness' limit in SketchUp.
Its built-in tolerance is ~1/1000": so if you do any operations [either by the native tools - like FollowMe or Solids - OR when using any plugin tools doing similar processes], which result in edges at or below that size, then those edges are not created - because SketchUp considers their two end points as being coincident.
With an edge missing any connected faces also fail to materialize, so then you get holes and stray lines in the result.
So if you are working on objects that might result in small a facets etc [e.g. they are of a small size with curved parts, or include the intersections of very complex triangulated meshes], then the well know workaround is to Scale up your object[s] x10 or even more: then do the operations - these should then give a good solid result, and finally you Scale back down to the original size.
Tiny geometry can exist after the re-Scale, but SketchUp cannot create it initially.

I was modelling this ship at "real" scale (it's about 200 metres long), so none of the edges should have ended up being small enough to cause problems with the lower limit in SketchUp, but scaling it up 5x did help later on when I was making a separate copy of the main model for 3D printing (using Outer Shell and BoolTools and Intersect Faces to merge all the components and Groups into a single solid). I still ran into plenty of issues (How can two objects which are solid before merging not still be solid after merging? Why was both Outer Shell and BoolTools allowing internal geometry to exist when merging two particular groups?) but I'm getting through it. I'll post the finished result (4 files - the original model, the solid command module, the solid accommodation module, and the solid main hull) once I'm done fiddling with getting the whole thing to become and stay solid.

FYI I was so desperate for proper booleans that I bought BoolTools. It was a waste of $10. It cannot properly handle complex curved faces during boolean operations; a subtraction of a square component from a round component fails to produce the same clean result as the native tools (broken edges, random missing lines -- the result of a boolean subtraction between two solids is not a solid, which to me is a deal-breaker). Very unhappy that I wasted $10 on a tool that is less helpful than Intersect Faces combined with lots of tedious manual line-drawing. I thus again look forward to OSCoolean being updated for SU 2014 with great anticipation.

@cotty said:

?
To clarify, I'm not sure any tool I won't use much after I finish this particular model is worth $10. I do 3D modelling pretty infrequently (I only use SketchUp; mostly because it's easy to use and also the free version is pretty flexible and I can export to STL) -- mostly for either really basic stuff that doesn't require boolean operations, or for the rare (once a year for a month or two) mega-project like this one.

@cotty said:

You can upload an example here and I will try it with the BoolTools, if this helps you...
I don't really know how to purposefully cause a solid-looking object to not be solid, but I know it has happened on a few occasions and even with the Solid Inspector, figuring out how to fix it is often difficult or confusing. I'd guess that extruding a profile twice (creating a new face on the second extrusion) might make an object no longer be solid in the eyes of SU...

Edit:
Just tested it: doing a push/pull and toggling "create new starting face" causes the resulting object to not be solid. If BoolTools can handle that kind of issue (internal faces) or missing faces (make a sphere, view hidden geometry, delete a single facet, make the sphere a group, attempt to boolean add/subtract/whatever with another solid or non-solid object), then I'd say it's definitely worth the $10, since not even the native tool can do that.

Cutting sections out of deformed spheres with high poly counts would be tedious to use intersect faces and manually delete the portions I don't want. Merging an extruded X profile with an extruded Y profile and an extruded Z profile is incredibly time-consuming to do manually. And manually making faces at all often results in non-solid objects, which would be ok if I wasn't planning to 3D print the shapes...

I'm not averse to spending extra time doing things, I just prefer the speed and accuracy of boolean operations for a lot of things.

I tried modelling this several years back and got to about the same point, but it took me months. Using boolean operations, I got to this state within a week. Without boolean operations I'm not sure how I can finish the engine block or the thrust vector cowl.

Edit:
Using Intersect Faces seems to work ok for objects with relatively simple geometry. It's just annoying to have to manually finish connecting vertices in order to make all the faces. Drape seems to work pretty well for merging flat profiles with complex shapes such as deformed spheres, but has the same problem in that I'd have to spend quite some time connecting opposite vertices to make the finishing faces. For the most part I suppose I can live without boolean operations at this point (since I've already finished the most complicated spheroid components). That said, I'll be eagerly awaiting an update of OSCoolean, and I'll keep BoolTools in mind just in case. I'd just buy SU Pro but $590 is so much money for a hobby tool, since I'm unlikely to use SU in my actual career.

@cotty - I saw BoolTools and it looks neat, but I wasn't sure it was worth $10.

Until I saw that it can handle coplanar faces. Does that mean I can perform boolean operations on non-solid groups/components? If so, I'm sold.

Is there any news on the update front for this plugin? It looks awesome, but I'm using 2014, and thus cannot use it. I got comfy using the built-in boolean tools, unaware that they were pro-only, as I hadn't closed SketchUp or rebooted my computer since I installed it. As a result, when I rebooted today I discovered to my horror that the boolean tool upon which I rely pretty heavily for reconstructing objects from profiles was no longer usable. It seems to me OSCoolean is the only free alternative. I'm unwilling to pay for a hobby tool (I model entirely for fun) which I may only use for a short while and leave to rust in the aether after I'm done with this project and abandon SU for months or years...so I guess I'll just have to hope you've had time to work on this plugin.